Cook potato and carrot in boiling water to cover 5 minutes. Add lima beans; cook 5 minutes or until crisp-tender. Drain vegetable mixture; set aside.
Cook onion in butter in a Dutch oven over medium heat, stirring constantly, until tender. Add flour; cook, stirring constantly, 1 minute. Add broth and 1 cup half-and-half; cook, stirring constantly, until mixture is thickened and bubbly. Stir in turkey and vegetable mixture. Stir in sage, salt, and pepper.
Spoon mixture into 4 (2-cup) ovenproof soup bowls.
Roll puff pastry to 1/8" thickness on a lightly floured surface. Cut circles of pastry large enough to cover tops of bowls (5" to 6"). Combine egg yolk and 1 tablespoon half-and-half; brush half of egg mixture onto edges of pastry circles. Invert over turkey mixture in each bowl. Fold edges under and crimp. Cut decorative shapes from remaining pastry, if desired, arranging cutouts in center of pies. Brush top of each pot pie with remaining egg mixture.
Bake at 400° for 15 to 20 minutes or until pot pies are golden. Serve hot.